Download Hormones and the Endocrine System

I.
Hormones
•
chemical messengers inside a body
o
relay a message from one part of body to another
II. Endocrine System
all cells, tissues, and organs involved in producing hormones
•
III. Categories of Hormones
A. pheromones
•
B.
act between two organisms, usually same species
endocrine hormones
1.
2.
act within an organism, some distance away from where produced
endocrine glands vs. exocrine glands
C. paracrine hormones
•
D.
act within an org., in cells adjacent to where they are produced
autocrine hormones
•
act within an org., in the same cells in which they are produced
Three different categories of hormones
IV. Basic Facts About Hormones
A.
B.
C.
hormonal activity/control is much slower than neural activity/control
transported in circulatory or lymphatic system
chemical nature of hormones
1. proteins
•
peptide hormones
2. lipids
a. sterols (4-ring structure)
b. prostaglandins (linear)
D. hormones work in a very specific manner
1. attach to receptor sites on their target cells
•
attachment is in a lock-and-key fashion
2. only affect their target cells
•
most cause powerful and important effects
Fig. 40.3
Target cell concept
E. rate of secretion determines short-term vs. long-term effects
1.
2.
F.
quick bursts  short-term effects
slow, steady secretion  long-term effects
hormone release
•
prompted by physical, chemical, and environmental cues
G. control of hormone secretion
1.
2.
negative feedback
releasing and inhibiting hormones
•
releasing hormones often cause release of stimulating hormones
o stimulate a target gland to release one or more of its hormones
3. other hormones with opposite effects
•
antagonistic hormones
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Some elements of hormone control
V.
Hormones and the Target Cell
A.
peptide hormones
1.
most interact with membrane
receptors on target cell
•
hormone on receptor (1st
messenger)  activates 2nd
messenger
o
cAMP, cGMP
2.
2nd messenger relays message
to nucleus by triggering an
enzyme cascade
•
series of reactions, each
using its own enzyme
3.
enzyme cascade releases an
end-product  causes an effect
or response
Fig. 40.4
Peptide hormones
B.
lipid hormones
1.
no 2nd messengers or enzymes
2.
directly effect gene action
3.
hormone diffuses through
membrane  moves into
nucleus  joins with receptor
proteins  activates a gene 
gene synthesizes a protein 
protein carries out response
VI. Invertebrate Hormones
A.
B.
source is often nervous system
involved in many aspects of life
1.
molting
•
periodic shedding of
exoskeleton
2.
metamorphosis
•
egg  larva  pupa  adult
Fig. 40.5
Lipid hormones
Fig. 40.2
An overview of
the human
endocrine system
VII. Human Endocrine System
A. pituitary gland (hypophysis)
1. anterior pituitary
•
releases 7 different hormones
o incl., gonadotropins
 hormones that affect the gonads
2. posterior pituitary
a. releases two categories of hormones
b. more directly controlled by nervous system than ant.
3. both halves controlled by hypothalamus
a. “hormone control center”
b. releasing and inhibiting hormones
Fig. 40.6
Hypothalamus and the pituitary gland
B.
thyroid gland and parathyroid gland
1.
2.
3.
parathyroid embedded within thyroid
regulation of metabolism and Ca
hyperthyroidism vs. hypothyroidism vs. goiter
C. pancreas
1. insulin vs. glucagon
a. great example of antagonistic hormones
b. both affect blood glucose levels
•
insulin lowers; glucagon raises
2. diabetes mellitus
Fig. 40.10
Regulation of blood
calcium level
Fig. 40.15
Regulation of blood
glucose level
D. adrenal glands
1. located on top of each kidney
2. usually release hormones in response to stress
3. adrenal cortex
• releases corticosteroids
o long-term responses to stress
4. adrenal medulla
• epinephrine (adrenalin) and norepinephrine
o short-term responses to stress
Fig. 40.11
Adrenal glands
E. ovaries
•
estrogen and progesterone
F. testes
•
testosterone
G. thymus gland
•
hormones involved in immune response
H. pineal gland
1. located deep inside brain
2. melatonin
• helps regulate daily rhythms of sleep and wakefulness
o circadian rhythms
3. some influence over hypothalamus and pituitary glands
I.
prostaglandins
1. lipid hormones of nonspecific origin
2. aid in birth process, blood clotting, and inflammation
Fig. 40.2
An overview of
the human
endocrine system